Shoulder Dislocation: Causes, Types, Symptoms, and Treatment

Why is my shoulder dislocated?

A shoulder dislocation occurs when the head of your humerus (upper arm bone) completely separates from the glenoid (socket) of your shoulder blade, most commonly due to a traumatic injury that forces the arm beyond its normal range of motion.

Understanding Shoulder Dislocation

The shoulder is the most mobile joint in the human body, a ball-and-socket articulation known as the glenohumeral joint. This exceptional mobility, however, comes at the cost of stability. The "ball" (humeral head) sits in a relatively shallow "socket" (glenoid fossa of the scapula). Stability is primarily provided by a complex network of soft tissues, including:

• Glenoid Labrum: A ring of cartilage that deepens the glenoid socket.
• Joint Capsule: A fibrous sac enclosing the joint.
• Ligaments: Strong bands of connective tissue (e.g., glenohumeral ligaments) that reinforce the capsule.
• Rotator Cuff Muscles: A group of four muscles (supraspinatus, infraspinatus, teres minor, subscapularis) and their tendons that surround the joint, actively stabilizing it and allowing for rotation.
• Scapular Stabilizers: Muscles that control the position and movement of the shoulder blade, which is crucial for proper shoulder mechanics.

A shoulder dislocation signifies a complete separation, distinguishing it from a subluxation, which is a partial or incomplete dislocation where the humeral head momentarily slips out of the socket and then returns.

Primary Causes of Shoulder Dislocation

Shoulder dislocations are predominantly caused by two main categories:

• Traumatic Injury: This is by far the most common cause. A significant force or impact can push the humeral head out of its socket. Common scenarios include:

  • Falls: Especially falling onto an outstretched arm (FOOSH) or directly onto the shoulder.
  • Sports Injuries: High-impact sports (football, rugby, hockey) or activities involving overhead movements and forceful contact (basketball, volleyball, wrestling, gymnastics) are frequent culprits.
  • Direct Blows: A direct impact to the shoulder can force it out of alignment.
  • Motor Vehicle Accidents: High-energy trauma can lead to dislocation.
  • Seizures or Electrocution: Violent muscle contractions can sometimes cause a dislocation, particularly posterior dislocations.

• Atraumatic or Less Common Causes: While less frequent, some individuals may experience dislocations with minimal or no significant trauma. This often relates to underlying issues:

  • Ligamentous Laxity: Generalized looseness in the joints due to genetic predisposition (e.g., Ehlers-Danlos syndrome) or repetitive activities that stretch the joint capsule over time (e.g., overhead athletes like swimmers or pitchers).
  • Previous Dislocation: Once a shoulder has dislocated, the soft tissues (labrum, capsule, ligaments) are often stretched or torn, making it significantly easier for the shoulder to dislocate again, even with less force. This is known as recurrent instability.
  • Muscle Imbalances or Weakness: Inadequate strength in the rotator cuff or scapular stabilizing muscles can compromise the dynamic stability of the joint, increasing susceptibility.

Types of Shoulder Dislocation

The direction in which the humeral head dislocates determines the type:

• Anterior Dislocation: The most common type (over 95%), where the humeral head moves forward and usually slightly downward. This often occurs when the arm is abducted (raised out to the side) and externally rotated, common in falls or throwing motions.
• Posterior Dislocation: Less common, occurring when the humeral head moves backward. This can result from a direct blow to the front of the shoulder or from violent muscle contractions (e.g., seizures, electrocution).
• Inferior Dislocation (Luxatio Erecta): The rarest type, where the humeral head dislocates directly downwards, often leaving the arm fixed in an overhead position. This requires extreme force.

Risk Factors for Shoulder Dislocation

Several factors can increase an individual's risk of experiencing a shoulder dislocation:

• Prior Dislocation: The single greatest risk factor for future dislocations. Damage to the labrum (e.g., Bankart lesion) or bone (e.g., Hill-Sachs lesion, glenoid bone loss) makes recurrence highly likely.
• Age: Younger individuals, particularly adolescents and young adults, are at higher risk of initial dislocation and, more importantly, recurrence, due to higher activity levels and more elastic soft tissues.
• Participation in Contact/Overhead Sports: Activities like football, rugby, wrestling, basketball, gymnastics, and throwing sports significantly elevate risk.
• Generalized Ligamentous Laxity: Individuals with naturally "loose" joints may be more prone.
• Anatomical Factors: A shallower glenoid fossa or other subtle anatomical variations can predispose someone to instability.
• Poor Shoulder Strength and Stability: Weakness in the rotator cuff or scapular stabilizing muscles.

Recognizing a Shoulder Dislocation

If you suspect a shoulder dislocation, you will likely experience:

• Sudden, Intense Pain: Often described as excruciating.
• Visible Deformity: The shoulder may appear "squared-off" or have an abnormal bulge under the skin (the humeral head) either in front, back, or below the joint.
• Inability to Move the Arm: Any attempt to move the arm will be met with severe pain and resistance. The arm may be held rigidly in an abnormal position.
• Swelling and Bruising: These may develop shortly after the injury.
• Numbness or Tingling: Due to potential nerve compression or stretching, particularly down the arm or into the hand.
• Muscle Spasms: Muscles around the shoulder may go into spasm, further immobilizing the joint and intensifying pain.

Immediate Action and Medical Treatment

If you suspect a shoulder dislocation, it is crucial to seek immediate medical attention.

• DO NOT attempt to reduce (put back in place) the shoulder yourself or allow anyone untrained to do so. This can cause further damage to nerves, blood vessels, or surrounding soft tissues and bones.
• Immobilize the Arm: Keep the arm as still as possible, perhaps by using a sling or simply holding it against the body.
• Apply Ice: To help reduce swelling and pain.

Upon arrival at a medical facility (emergency room or urgent care), medical professionals will:

• Confirm Diagnosis: Through physical examination and X-rays to confirm the dislocation and rule out any associated fractures (e.g., greater tuberosity fracture, glenoid rim fracture). An MRI may be ordered later to assess soft tissue damage (labrum, ligaments, rotator cuff).
• Reduction: The shoulder will be gently manipulated back into place (reduced) by a trained medical professional, often under sedation or anesthesia to relax the muscles and minimize pain.
• Post-Reduction Care: After reduction, the arm will typically be immobilized in a sling for a period to allow initial healing of the stretched or torn tissues.

Preventing Recurrence and Rehabilitation

Once a shoulder has dislocated, the risk of recurrence is significant, especially in younger, active individuals. Comprehensive rehabilitation is vital:

• Physical Therapy: A structured program is essential. It will focus on:
  • Pain and Swelling Management: Initial phase.
  • Restoring Range of Motion: Gradually and safely.
  • Strengthening: Emphasizing the rotator cuff muscles and scapular stabilizers to improve dynamic stability.
  • Proprioception Training: Exercises to improve the body's awareness of joint position, which is critical for preventing future dislocations.
  • Gradual Return to Activity: A progressive plan to return to daily activities, work, and sports.
• Activity Modification: Avoiding positions that put the shoulder at risk (e.g., extreme abduction and external rotation).
• Surgical Intervention: May be recommended for:
  • Recurrent Dislocations: Especially in young, active individuals.
  • Significant Soft Tissue Damage: Such as a large Bankart lesion (tear of the labrum from the glenoid) or rotator cuff tear.
  • Bone Loss: If there's a significant Hill-Sachs lesion (dent in the back of the humeral head) or glenoid bone loss, which can compromise stability.
  • Failed Conservative Management: If non-surgical approaches do not prevent recurrence.

When to Seek Professional Help

Any suspected shoulder dislocation warrants immediate medical attention. Furthermore, if you have experienced a shoulder dislocation and continue to have pain, instability, recurrent "slipping" sensations, or difficulty returning to your previous activity levels, consult with an orthopedic specialist or sports medicine physician. Early and appropriate management is key to optimizing recovery and preventing long-term complications.